All for the last sentence. A population being healthier longer is going to be (for the most part, insert hypothetical social repercussions here) only beneficial for everyone. Essentially everyone earns their keep longer. However we need to avoid the "at all costs" approach to long life as most avenues will make us biologically functional longer but with extended senility/frailty which is worse than our current situation. Also evolution. Or if that's a scary word for you: generational genetic upgrading. Currently healthy populations keep competitive in the ever changing environments of the world through the death/birth cycle. You're born, you sexually mature, you mate and birth genetically superior copies (marginally and for that moment in time), you raise them til they're capable of reproducing, then you start to break down and eventually die. It ensures that organisms that can't physically, dynamically adjust to changing conditions have a means of improving. Also genetic recombination to innovate, evolve and reduce the damage that diseases can do.
Long story short: longer youth = good, prolonged aging = bad.
